The present invention relates to a semiconductor device and, more particularly, to a technique effectively applied to a semiconductor device such as a microcomputer or a system LSI having a power shutoff function for reduction in power consumption.
For example, Japanese Unexamined Patent Publication No. 2003-032399 discloses an image processor having a selection switch capable of switching a power to be supplied to a volatile memory between a main power supply or a standby power supply, and means for controlling the selection switch. The means for controlling the selection switch includes a main power supply level detector for detecting a voltage drop accompanying stop of the main power supply and switching the selection switch to the standby power supply side. With the configuration, in a state where image data is held in the volatile memory, the image processor can shift to a low-power standby mode without dissipating the image data.